I added your breps. Extended speckle object with “renderMaterial” being the key (not RenderMaterial), made sure it was not detached and it worked. Take a look
PS: Your Grasshopper script looks overcomplicated. You can directly connect your stream URL into the Send node and it will pick up your account automatically. And you don’t have to convert your Breps into Speckle equivalents. We do that when you extend your object.